Engineering & Mining Journal

AUG 2017

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

Contents of this Issue

Navigation

Page 34 of 99

MINE DEVELOPMENT
AUGUST 2017 • E&MJ 33 www.e-mj.com
that material is being drawn from the
correct locations. "The goal is to get the
best monitoring data possible," Steffen
said, "And ideally the beacon would be
installed in a high density in the cave."
The beacons are usually installed into
drill holes. "To come up with a Beacon in-
stallation program, an iterative approach
using the system's analysis software is
common." This allows the installation to
be optimized for performance and cost.
When envisioning an installation, the
miner should first determine the primary
areas of interest in the cave. "Geological
domains and their rock mass properties
determine cave-ability," he said. "Expect-
ed fragmentation and cave propagation in
conjunction with the mine plan will drive
this point."
Next, use of existing drill holes and
the cost of additional drilling should be
considered. "The availability of drilling
locations will determine the lengths of
the required holes and if it is technical-
ly viable to drill into the volumes of in-
terest," Steffen said. "The hole lengths
will define the drilling costs." Ultimately,
costs can determine how many and where
the beacons are located.
When a basic plan is hatched, Elexon
calculates the predesign feasibility, Stef-
fen said. "To assess installation design,
we perform sensitivity simulations based
on proposed installation designs," he
said. "If available, we include numerical
modeling results provided by packages
such as Itasca's Rebop."
Once installed, the beacons move with
the caved rock. Range measurements
from the detectors are combined on a reg-
ular basis to calculate a beacon's position
in three dimensions and its movement
over time.
To survive the trip, the beacons, which
are comprised of batteries, electronics,
magnet and motor assembly, are encased
in a shell designed to withstand immense
pressure. The shell can withstand forces
such as localized pressure from "tons of
rock leaning onto it, impact forces from
dropping from the cave back through
an airgap onto the muck pile and fluid
pressure of a head pressure of more than
1,000 m encountered during grouting,"
Steffen said. "The Beacon has internal
features that protect batteries, electron-
ics and spinning magnets from impacts."
The detectors also can withstand high flu-
id pressure, he said.
Beacons get extracted through the
drawpoints by LHDs, Steffen said. "The
LHD then dumps them with the ore."
Working in conjunction with Elexon's
Networked Smart Marker System, Cave
Tracker can paint a picture of anomalies
in muck that could pose safety threats,
such as air gaps. The markers, which are
like wireless TDRs, detect movement in
the range of centimeters, whereas Cave
Tracker detects it in the range of meters,
Steffen said. An advantage of the Net-
worked Smart Markers and the beacons
is they require no cables that can be
snapped by hole displacements. "Net-
worked Smart Markers measure the prop-
agation of the seismogenic zone and the
cave back while Cave Tracker will detect
mass movement," he said. "Combining
the data can be used to indicate the pres-
ence of an air gap."
Knowing the location and size of an
air gap empowers the miner to manage
it. Meanwhile, real-time data on cave
propagation will empower miners to plan
with exactitude, improve process con-
trols and thus reduce dilution, Steffen
said. "Efficiency gains are to be expected
through better control over cave growth,
through delayed waste entries and im-
proved ramping up of production," he
said. "For future caves, extraction, un-
dercut layouts, and block heights can be
optimized for better recovery and lower
development cost."
Exact planning, better processes,
lower development costs and optimized
ore recovery will significantly offset the
drilling costs that accompany deploying
the system, Steffen said. "The financial
benefits through higher recovery, lower
dilution and better predictability of mine
performance would be in the hundreds
of millions of dollars for a mid- to large-
scale project," he said. "Compare that
to an investment into drilling monitoring
holes and installing Cave Tracker equip-
ment, for which the costs would be lower
than or around $10 million for a large-
scale installation."
Elexon is currently researching other
mining applications for magnetic bea-
con-based systems, he said.
Inventory Tracking and
Draw Cards
Last June, Glencore announced the de-
ployment of Modular's DISPATCH Under-
ground 2015 Fleet Management System
(FMS) to its George Fisher zinc mine in
North Queensland, Australia. There the
system is being rolled out to help man-
Glencore's George Fisher mine will reportedly roll out DISPATCH 2015 Underground over an extended project period,
the miner reported last year. Above, new pipeline installation at the mine. (Photo: Glencore)